Ulnar nerve elongation and excursion in the cubital tunnel after decompression and anterior transposition

Post-Operative Assessment of Ulnar Nerve Tension Using Shear-Wave Elastography

BACKGROUND

Ulnar nerve compression at the elbow level is the second-most common entrapment neuropathy. The aim of this study was to use shear-wave elastography for the quantification of ulnar nerve elasticity in patients after ulnar nerve decompression with anterior transposition and in the contralateral non-operative side.

METHOD

Eleven patients with confirmed diagnosis and ulnar nerve decompression with anterior transposition were included and examinations were performed on an Aixplorer^TM ultrasound system (Supersonic Imagine, Aix-en-Provence, France).

RESULTS

We observed significant differences at 0-degree (p < 0.001), 45-degree (p < 0.05), 90-degree (p < 0.01) and 120-degree (p < 0.001) elbow flexion in the shear elastic modulus of the ulnar nerve in the operative and non-operative sides. There were no statistically significant differences between the elasticity values of the ulnar nerve after transposition at 0-degree elbow flexion and in the non-operative side at 120-degree elbow flexion (p = 0.39), or in the ulnar nerve after transposition at 120-degree elbow flexion and in the non-operative side at 0-degree elbow flexion (p = 0.09).

CONCLUSION

Shear-wave elastography has the potential to be used postoperatively as a method for assessing nerve tension noninvasively by the estimation of mechanical properties, such as the shear elastic modulus.

The effect of operative technique on ulnar nerve strain following surgery for cubital tunnel syndrome

BACKGROUND

The aim of this study is to compare the amount of strain on the ulnar nerve based on elbow position after in situ release, subcutaneous transposition, submuscular transposition, and medial epicondylectomy.

METHODS

Six matched cadaver upper extremity pairs underwent ulnar nerve decompression, transposition in a sequential fashion, while five elbows underwent medial epicondylectomy. A differential variable reluctance transducer (DVRT) was placed in the ulnar nerve. An in situ release, a subcutaneous transposition, and a submuscular transposition were performed sequentially with the strain being measured after each procedure in neutral, full elbow flexion, and extension positions. The strain was then averaged and compared for each procedure. Five cadavers underwent medial epicondylectomy and were similarly tested.

RESULTS

After the in situ release, there was no statistically significant change in strain in either flexion or extension. After a subcutaneous transposition, there was a statistically significant decrease in strain in full elbow flexion but not in extension. Similarly after a submuscular transposition, there was a statistically significant decrease in strain in full flexion but not in extension. There was not a statistically significant change in strain with medial epicondylectomy.

CONCLUSION

An in situ release of the ulnar nerve at the elbow may relieve pressure on the nerve but does not address the problem of strain which may be the underlying pathology in many cases of ulnar neuropathy at the elbow (UNE). Transposition of the ulnar nerve anterior to the medial epicondyle addresses the problem of strain on the ulnar nerve. In addition, it does not create an increased strain on the ulnar nerve with elbow extension.

The "hierarchical" Scratch Collapse Test for identifying multilevel ulnar nerve compression

BACKGROUND

The Scratch Collapse Test (SCT) is used to assist in the clinical evaluation of patients with ulnar nerve compression. The purpose of this study is to introduce the hierarchical SCT as a physical examination tool for identifying multilevel nerve compression in patients with cubital tunnel syndrome.

METHODS

A prospective cohort study (2010-2011) was conducted of patients referred with primary cubital tunnel syndrome. Five ulnar nerve compression sites were evaluated with the SCT. Each site generating a positive SCT was sequentially "frozen out" with a topical anesthetic to allow determination of both primary and secondary ulnar nerve entrapment points. The order or "hierarchy" of compression sites was recorded.

RESULTS

Twenty-five patients (mean age 49.6 ± 12.3 years; 64 % female) were eligible for inclusion. The primary entrapment point was identified as Osborne's band in 80 % and the cubital tunnel retinaculum in 20 % of patients. Secondary entrapment points were also identified in the following order in all patients: (1) volar antebrachial fascia, (2) Guyon's canal, and (3) arcade of Struthers.

CONCLUSION

The SCT is useful in localizing the site of primary compression of the ulnar nerve in patients with cubital tunnel syndrome. It is also sensitive enough to detect secondary compression points when primary sites are sequentially frozen out with a topical anesthetic, termed the hierarchical SCT. The findings of the hierarchical SCT are in keeping with the double crush hypothesis described by Upton and McComas in 1973 and the hypothesis of multilevel nerve compression proposed by Mackinnon and Novak in 1994.

Stabilized subcutaneous transposition of the ulnar nerve

We treated 50 patients (average age 47.9 years) with a stabilized subcutaneous transposition of the ulnar nerve. The average follow-up period was 42.4 months. The indication was cubital tunnel syndrome in 19 patients and injuries around the elbow in 31 patients. Postoperatively, satisfactory results were obtained in all the patients, and there was no complication or aggravation of the preoperative symptoms. None of the patients experienced slipping back of the nerve to the cubital tunnel. In the 31 patients with injuries around the elbow, there was only one patient with transient aggravation of parasthaesiae in the ulnar nerve region. Stabilized subcutaneous transposition is a simple and less invasive procedure that can facilitate decompression and prevent slipping back of the nerve. This procedure also can be applied to patients with injuries around the elbow that require ulnar nerve transfer.